Mechanical engine protectors are available which shut down a diesel engine when crankcase pressure reaches or exceeds a predetermined limit. The increased pressure is typically caused by scored liners, broken or badly worn pistons or rings, or other internal part failure. Such an engine protector is shown and described in U.S. Pat. No. 2,600,810 wherein the increased pressure acts to flex a diaphragm which operates a switch wired into the governor circuit to shut down the engine and activate a flashing red warning light. Although mechanical engine protectors are effective in detecting internal part failure before serious crankcase damage occurs, known protectors have some shortcomings.
When currently known engine protectors are used on locomotives "false" shut downs sometimes occur as the locomotive exits a tunnel. The train leaving a tunnel creates low pressure in the tunnel causing the protector diaphragm to flex and shut down the engine.
Those concerned with these and other problems recognize the need for an improved electronic engine protector.